The present invention relates to cooling systems for internal combustion engines, such as those used in motor vehicles; and more particularly to mechanisms for releasing gas contained in such cooling systems.
Internal combustion engines typically are cooled by a sealed system through which liquid coolant flows. A pump forces the coolant from a radiator through passages in the engine block during which the coolant absorbs heat from the engine. The heated coolant returns to the radiator where air passing over cooling fins removes heat from the coolant before the pump forces the coolant back into to the engine block.
Although the cooling system is sealed, it has been discovered that combustion gases in the engine cylinders can leak past gaskets and enter the cooling system passages. This is especially prevalent in high compression engines, such as diesel engines commonly used in trucks. Air may also be drawn into the cooling system from leaks on the suction side of the pump.
Such gases may accumulate in pockets of the coolant passages and adversely affect the removal of heat from the adjacent part of the engine block. A significant problem, that results from gases in the cooling system, is cavitation erosion of metal surfaces inside the engine block. Turbulence of the liquid coolant flowing through the cooling system divides the gas into tiny bubbles which impact the passage walls. Over a relatively short time repeated impacts of the gas bubbles produces pits in the passage walls resulting in engine deterioration.